Field of the Invention
The invention is directed to the field of fumigating imported or exported matter such as produce or wood products and more specifically, improvements in the “tarpless” fumigation of same.
Description of the Related Art
United States Federal regulations require that imported fruits, vegetables, and other perishable or organic matter be inspected upon arrival to United States Ports of Entry. Under certain circumstances, an inspector may determine that such perishables must be fumigated before they are allowed to leave United States Customs Quarantine Areas.
The fumigation process, as well as the requirements for packing perishables in containers for fumigation present several problems. First, because fumigation requires circulation, shippers must leave sufficient room in the container for air to circulate. Generally this requires that goods be stacked no higher than eighteen inches from the top of the container, or twenty percent air space, depending on the fumigation method. Because the goods could otherwise be packed to within five inches of the top of the container, this results in less than optimal shipping configurations.
Second, and as stated previously, the fumigation process can present several problems. The standard method of fumigation is known as tenting, whereby a tarpaulin is first draped over the container which must be weighted down or otherwise sealed against the ground to act as a gas barrier. All of the conduits, gas, electrical and other lines must be fed under the tarp. This method inherently utilizes a greater amount of fumigant than would otherwise be necessary to fumigate only the container. Furthermore, the tenting process generally cannot be carried out on a windy day. Lastly, the tenting process exposes the contents of the cargo container to a relatively large amount of ambient air, which is not desirable in the case of a refrigerated container, which must be shut off during the fumigation process.
Other methods of fumigation have sought to eliminate the tarpaulin. One such method of “tarpless” fumigation requires transporting the container to a fixed fumigation site, unloading the contents of the container, fumigating, and reloading the contents of the container. This method is obviously quite time consuming and not desirable in the case of refrigerated perishables. This method further increases the risk of contamination as removing the cargo from the container would substantially increase the opportunity for insects and pests to escape the quarantine.
Another such method of tarpless fumigation involves first opening the doors of the container and placing a second door module in the opening which acts as a seal for the fumigant. This method fails to address the problem with exposure of refrigerated contents to ambient air and furthermore, still requires shippers to comply with the inefficient packing requirement of eighteen inches of head space or twenty percent air space.
The current invention is directed toward a system and method for fumigating a cargo container that allows for more efficient packing of cargo, better preserves the internal temperature of refrigerated containers, and addresses other issues known in the art.